Periods affect women's brains

Help may soon be on its way for women who live with the pain of premenstrual syndrome (PMS), and for those who live with them. Researchers have begun to investigate what happens in the brain as a woman's hormones surge before her period.

So far, they say, the results tentatively indicate that a boost in brain activity in an emotional centre of the brain might help to keep some women more emotionally stable, even as their hormones go on a roller-coaster ride.

Despite huge amounts of interest in PMS and the drugs that might combat it, surprisingly little research has looked at how the brain behaves during this turbulent time, says David Silbersweig, a neurologist at Cornell University's Weill Medical College in New York City. He notes that among women of reproductive age, roughly 75% report mood swings or physical discomfort during their premenstrual phase.

Silbersweig and his colleagues recruited 12 women who experience consistently steady moods during their cycle, to create a baseline for future studies of women with huge mood swings. The researchers conducted tests and brain scans twice during the subjects' monthly cycles: once during the premenstrual phase and again about ten days later.

The team asked participants to press a button in response to negative and positive words flashing across a screen. As the subjects completed the task, their brains were scanned using functional magnetic resonance imaging, which measures tiny metabolic changes in the brain. The team focused its attention on the medial orbitofrontal cortex, a brain region implicated in emotion control.

Highs and lows

The women's emotional response to the words did not vary significantly during the month, supporting the idea that they did not suffer from PMS. But their brain scans did show a change: they had a significant increase in activity in the medial orbitofrontal cortex during the premenstrual part of their cycle. The findings appear in the Proceedings of the National Academy of Sciences1.

The team speculates that this boost of brain activity could be what helps these women to keep their emotions steady as their hormones surge. They have started collecting similar data on brain activity from women who do report intense mood swings before their period to see if they lack this brain boost. Researchers will also have to look at varying hormone levels between women to assess these studies, of course.

It is early days for research on brain activity and emotion, notes neuroscientist Jill Goldstein of the Harvard Medical School in Boston, Massachusetts. She says researchers have only just begun to use these scans to see how hormones affect mental processing.

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But experts agree that brain studies will provide an interesting avenue into studying mood swings, and possibly in designing pharmaceuticals to ease the pain of PMS.

Chris Ryan, with the National Association for Premenstrual Syndrome in Kent, UK, says this study "adds to the compelling evidence that the menstrual cycle is a key factor influencing the psychological well-being of women of reproductive age". Ryan adds that understanding the mental aspects of PMS should make for "more sensitive treatment" for sufferers. "We may then finally see an end to the blanket prescription of antidepressants for symptoms that are specifically related to menstruation."